I had to do this for a client recently. Because I don't have access to ABL in this particular case, this is what I did.
SELECT CONCAT(CONCAT(RIGHT(REPLACE(CAST((CAST('1/1/1970' AS DATE))+(CAST((("my_table"."my_date")/86400) AS INT)) AS VARCHAR(10)),'/',''),4), LEFT(REPLACE(CAST((CAST('1/1/1970' AS DATE))+(CAST((("my_table"."my_date")/86400) AS INT)) AS VARCHAR(10)),'/',''),2)), LEFT(RIGHT(REPLACE(CAST((CAST('1/1/1970' AS DATE))+(CAST((("my_table"."my_date")/86400) AS INT)) AS VARCHAR(10)),'/',''),6),2)) AS yyyymmdd
FROM pub.my_table